With more than 583,000 square feet, Northborough Crossings becomes the firm’s largest property in the state. Equity One also owns Webster Plaza, a 200,000-square-foot shopping center in Webster that includes a Kmart and a Shaw’s Supermarket.

WORCESTER — The Massachusetts Nurses Association has filed an unfair labor practice charge against UMass Memorial Medical Center, accusing the hospital of forcing certain nurses to work on Christmas in violation of their contract.

The union, which is in tense contract negotiations with UMass Memorial, said in a statement Friday that nurses are being forced to work Christmas Day, even though they worked on Thanksgiving and are scheduled to work on New Year’s. The union is seeking an injunction with the National Labor Relations Board.

Nurses contend the move is retaliation for their picketing and public criticism of UMass Memorial in recent days.

The hospital said five nurses have been asked to work on Christmas.

“Over the past month, the Medical Center has experienced a significant increase in patients seeking care,” UMass Memorial said in a prepared statement. “That is why our contract gives the Medical Center the legal right to assign nurses to work on a holiday under the present circumstances. We would not assign this handful of nurses to work on Christmas unless we had to, and we’re doing everything we can to seek volunteers and per diems so that nurses can enjoy the holidays with their families.”

FRAMINGHAM— TJX Companies Inc., parent company of T.J. Maxx, Marshalls and HomeGoods, announced Friday that it has acquired Sierra Trading Post, an off-price Internet retailer based in Cheyenne, Wyo., for $200 million.

Sierra Trading Post, a privately held company with more than $200 million in annual revenues, launched its e-commerce business in 1999.

TJX CEO Carol Meyrowitz said in a press release that the acquisition will provide TJX with immediate scale, capabilities and infrastructure as it launches its own e-commerce sites for TJX brands.